Discount Calculator
Enter the original price and the discount to see what you’ll pay and what you save — or enter two prices to find the percentage off. Stacked discounts are handled correctly.
How it works
Sale price = price × (100 − discount) ÷ 100. A £120 jacket at 30% off is 120 × 0.70 = £84, saving you £36.
Percentage off = (original − sale) ÷ original × 100. A drop from £250 to £187.50 is (62.50 ÷ 250) × 100 = 25% off.
Stacked discounts multiply rather than add: 20% off plus an extra 10% at checkout is 28% off in total, not 30% (0.80 × 0.90 = 0.72). The calculator shows the true combined percentage.
FAQ
How do I work out 20% off a price?
Multiply the price by 0.80: a £65 item at 20% off costs £52. The general rule is price × (100 − discount) ÷ 100. A quick mental shortcut is to find 10% by moving the decimal point one place (£6.50), double it (£13) and subtract that saving from the original price.
Why is 50% off plus 20% off not 70% off?
Because the second discount applies to the already-reduced price. A £100 item at 50% off costs £50; a further 20% off that is £40 — a total saving of 60%, not 70%. Retailers rely on this difference in “extra % off sale items” promotions, so always check the final price rather than adding the percentages.
How do I check a sale price is genuine?
Compare against the price history, not just the ticket. UK guidance (CMA/CTSI pricing practices) says a “was” price should be the price the item genuinely sold at recently. Work out the real percentage off with this calculator — if a “70% off” claim is measured against an inflated was-price, the true discount from the typical selling price is often far smaller.